DesignTheory.org is the official website of a research project hosted at the School of Mathematical Sciences at Queen Mary, University of London, and funded by the UK Engineering and Physical Sciences Research Council. The goal of the project is "to cover theoretical, computational, and statistical aspects of combinatorial designs" and to develop an online database of various resources for Design...

Eric Weisstein's World of Science supplies great, online encyclopedias in astronomy, physics, chemistry, and mathematics, as well as a biography of renowned scientists. Users can find excellent, concise explanations of countless concepts. The website is well linked and, therefore, easy to traverse. Everyone, from grade school students to competent professionals, can utilize this amazing resource...

It's hard to believe it's all free! This trove of information from thefreedictionary.com offers all sorts of information on math. From algebra and integers to derivatives and polynomials, it's all here. By scrolling over or clicking on a link, the visitor is treated to a sometimes whopping amount of information about the given topic. For those simply interested in math, math lovers, or possibly a...

Mathworld, hosted and sponsored by Wolfram Research, Inc., is an online mathematics encyclopedia intended for students, educators, math enthusiasts, and researchers. This amazing resource was compiled over 12 years by Eric Weisstein with assistance from the mathematics and Internet communities, and continues to be updated. (Weisstein also authored the ScienceWorld site, which contains material...